In an information processing apparatus wherein the model-specific data must be preserved even after the information processing apparatus is powered off, the data stored in a nonvolatile memory 81 is developed in a system memory 82 which can be accessed faster than this nonvolatile memory 81 when powered on, as shown in FIG. 9. Then the processor 83 accesses the data on the system memory 82, whereby deterioration of the nonvolatile memory 81 due to frequent access is avoided and the system operation speed is increased.
In such an information processing apparatus, the data having been developed from the nonvolatile memory 81 into the system memory 82 may be changed to assume a different value during the operation. When power is turned off, the data in the system memory 82 must be saved into the nonvolatile memory 81, as shown in FIG. 10.
In this case, when the start of power-off operation has been detected according to a reduction in voltage (T1), the trigger signal TS representing the result of this detection is generated, and the saving (SV) of the corresponding data into the nonvolatile memory starts in response to this trigger signal TS, as shown in FIG. 11. Under the normal working condition, this saving operation (SV) can be terminated with sufficient lead time before the power is turned off (Toff), even if started after the occurrence of the trigger signal TS.
However, as shown in FIG. 12, when operation is made under the severe power conditions (e.g., instability and reduction of voltage), the time duration (Td) between occurrence of the trigger signal TS (T1) and actual turning off of the power (Toff) is shorter than expected. This may result in failure of data saving (the data having failed in the saving operation is indicated by “E” in the drawing). To avoid this, it is a common practice to preset the amount of data to be saved from the system memory to the nonvolatile memory when powered off, assuming a possible operation under poor power conditions.
In the meantime, a proposal has been made of a technique of verifying whether or not the writing of data into the nonvolatile memory has terminated incomplete in the middle of operation in the event of unexpected turning off of the power. For example, a memory area is divided into blocks, and a writing termination flag corresponding to each block is set, whereby it is possible to determine the blocks wherein writing operation has terminated successfully (e.g., Japanese Unexamined Patent Application Publication No. H10-240629).
As described above, when setting the amount of data to be saved from the system memory to the nonvolatile memory when power is turned off, a possible operation under poor power conditions is taken into account, and this amount is set at a rather smaller level. Under favorable power conditions, the amount of the data developed from the nonvolatile memory to the system memory is preferably maximized so that the frequency of access to the nonvolatile memory is minimized.
However, in the conventional art disclosed in the Japanese Unexamined Patent Application Publication No. H10-240629, it is possible to verify whether or not the writing of data in the nonvolatile memory has terminated incomplete in the middle of operation. If the saving of the data has terminated before the power is turned off, this technique fails to provide information showing the possible time allowance from the termination of saving operation to the power-off operation and information for the possibility of increasing the amount of data to be saved.
One object of the present invention is to solve these problems and to provide an information processing apparatus capable of verifying the reliability of the data having been saved to the nonvolatile memory when powered off, and providing information for changing the amount of data to be saved in the nonvolatile memory.